The role of short-lived climate forcers in limiting overshoot and returning warming well below 1.5°C

The 1.5°C warming limit enshrined in the Paris Agreement remains the critical benchmark for avoiding the most severe impacts of climate change. However, after decades of insufficient climate action, the world could exceed this threshold as early as 2030.1 Given the imminence of overshoot, policy focus must now shift to reducing its magnitude and duration.  Recent analysis shows that overshoot can be limited, and that warming can be brought back well below 1.5°C this century.2 However, delivering this requires robust evidence on how different mitigation actions shape temperature outcomes over time.

Previous studies have underscored that pairing deep reductions in carbon dioxide (CO2) emissions, primarily through the transition away from fossil fuels (TAFF), with targeted mitigation of short-lived climate forcers (SLCFs) – including methane (CH4), hydrofluorocarbons (HFCs), and black carbon (BC) – is essential to limiting near- and long-term warming while also delivering important air quality and health co-benefits.2–8 Since SLCFs remain in the atmosphere for much shorter periods than CO2, and have higher global warming potentials, cutting their emissions can deliver rapid temperature benefits.9

While there is consensus that SLCF mitigation is essential, estimates of how much it contributes to limiting warming vary widely between studies,3,8,10 due to differences in scenario assumptions and experimental design. Moreover, since these studies were published, greenhouse gas emissions have continued to rise and new research and mitigation pathways have become available.11,12 Decision-makers therefore require updated, quantitative evidence on how SLCF mitigation shapes temperature outcomes, both on its own and in conjunction with other levers, to inform policy design and investment decisions.

To address these needs, this new brief draws on the latest global emissions pathways from integrated assessment models (IAMs) to quantify the role that targeted SLCF reductions play in limiting overshoot and returning warming back well below 1.5°C, relative to and in combination with three other mitigation levers, namely TAFF, action to reduce land use, land use change and forestry emissions (LULUCF), and novel carbon dioxide removal (CDR). It quantifies how each of these levers, in isolation and in combination, can help reduce the rate of global warming, limit peak temperatures, and contribute to getting back below 1.5°C before 2100, while also assessing their limitations.